Thursday, April 25, 2019

Three-antibiotic cocktail clears 'persister' Lyme bacteria in mouse study

A new study from researchers at the Johns Hopkins Bloomberg School of Public Health found that a slow-growing variant form of Lyme bacteria caused severe symptoms in a mouse model. The slow-growing variant form of Lyme bacteria, according to the researchers, may account for the persistent symptoms seen in ten to twenty percent of Lyme patients that are not cured by the current Lyme antibiotic treatment.

Wednesday, April 24, 2019

Mepron - Helps knock-off Babesia. But how much to prescribe?

Yes, Mepron, despite how weird it looks (like yellow paint) it's a useful medicine. I took ot for about a year once, and it cleared up a lot of the issues in me old cranium department."

"For mepron to work you have to push the dose- 5cc tid for 5 months minimum and must be taken with a huge amount of fat- in absorption studies, the test subjects had 23g of fat with each dose! I had ordered blood level measurements after the third week, goal being 20+, but this test may no longer be available.

I use artemesinin SOD from Researched Nutritionals, but as with all artemesia products there must be a regular break in treatment- typically 3 weeks on and one off.

Cryptolepis, green tea egcg and sida are commonly added.
Specialty OTCs from Byron White and Susan McCamish help some but not others, and some have a hard time tolerating a full dose.
I also like to add transfer factors."

I think'll just file this, since I have already done that treatment. Just thought I would spread the word. 


Tuesday, April 23, 2019

Tiny, larval ticks can pack a wallop

Wed Mar 27, 2019 6:43 am (PDT) . Posted by: 

"Rick Laferriere" ri_lymeinfo 

*Study finds tiny larval ticks can transmit /Borrelia miyamotoi/*
/Lyme Science Blog/, by Daniel Cameron, MD, MPH, Mt. Kisco, New York
Dr. Cameron is a nationally recognized leader for his expertise in the 
diagnosis and treatment of Lyme disease and other tick-borne illnesses.

March 25, 2019

Nymphal and adult black-legged ticks, also known as deer ticks, harbor a 
growing number of pathogens.

But researchers are now discovering that larval ticks, which are even 
smaller, may pose an equal threat to public safety as a new study 
describes larval ticks infected with the tick-borne bacteria /Borrelia 

*Read the Complete Blog Entry*: 

*Read more of Lyme Science Blog at*: 

*Contact**Dr. Daniel Cameron*: <>


Related reading:
*Vertical transmission rates of /Borrelia miyamotoi/ in /Ixodes 
scapularis/ collected from white-tailed deer *
Han S, Lubelczyk C, Hickling GJ, Belperron AA, Bockenstedt LK, Tsao JI.
/Ticks and Tick-borne Diseases/. 2019 Feb 26. pii: S1877-959X(18)30088-8.


/Borrelia miyamotoi/is a relapsing feverspirochetetransmitted by ticks 
in the /Ixodes ricinus/ complex. In the eastern United States, /B. 
miyamotoi/ is transmitted by /I. scapularis,/ which also vectors several 
other pathogens including /B. burgdorferi/sensu stricto.

In contrast to Lyme borreliae, /B. miyamotoi/can be transmitted 
vertically from infected female ticks to their progeny. Therefore, in 
addition to nymphs and adults, larvae can vector /B. miyamotoi/to 
wildlife and human hosts. Two widely varying filial infection prevalence 
(FIP) estimates - 6% and 73% - have been reported previously from two 
vertically infected larval clutches; to our knowledge, no other 
estimates of FIP or transovarial transmission (TOT) rates for /B. 
miyamotoi/have been described in the literature. Thus, we investigated 
TOT and FIP of larval clutches derived from engorged females collected 
from hunter-harvested white-tailed deer in 2015 (n = 664) and 2016 
(n = 599) from Maine, New Hampshire, Tennessee, and Wisconsin.

After engorged females oviposited in the lab, they (n = 492) were tested 
for /B. miyamotoi/infection by PCR. Subsequently, from each clutch 
produced by an infected female, larval pools, as well as 100 individual 
eggs or larvae, were tested. The TOT rate of the 11 infected females was 
90.9% (95% CI; 57.1–99.5%) and the mean FIP of the resulting larval 
clutches was 84.4% (95% CI; 68.1–100%).

Even though the overall observed vertical transmissionrate (the product 
of TOT and FIP; 76.7%, 95% CI; 44.6–93.3%) was high, additional 
horizontal transmission may be required for enzootic maintenance of /B. 
miyamotoi/ based on the results of a previously published deterministic 
model. Further investigation of TOT and FIP variability and the 
underlying mechanisms, both in nature and the laboratory, will be needed 
to resolve this question. Meanwhile, studies quantifying the 
acarological risk of /Borrelia miyamotoi/ disease need to consider not 
only nymphs and adults, but larval /I. scapularis/ as well.

Tuesday, April 16, 2019

Inflammation and infections contributing to PD, ALS and ALZ

RNA Sequencing Reveals Small and Variable Contributions of Infectious Agents to Transcriptomes of Postmortem Nervous Tissues From Amyotrophic Lateral Sclerosis, Alzheimer's Disease and Parkinson's Disease Subjects, and Increased Expression of Genes From Disease-Activated Microglia.

Author information

Neurodegeneration Therapeutics, Inc., Charlottesville, VA, United States.
Parkinson's and Movement Disorders Center, Virginia Commonwealth University, Richmond, VA, United States.
Department of Medical Genetics, Virginia Commonwealth University, Richmond, VA, United States.


Nervous tissues from both humans with neurodegenerative diseases (NDD) and animals with genetic models of human NDD, such as rare monogenic causes of Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), show activated microglia, suggesting a potential causal role for inflammation in pathogenesis of NDD. We performed paired-end (PE) RNA sequencing (RNA seq) of total RNA's extracted from frozen sections of cervical spinal cords from ALS and CTL subjects, frontal cortical gray matter ribbons of AD and CTL subjects, and ventral midbrains of PD and CTL subjects. Trimmed PE reads were aligned against the hg38 human transcriptome using Tophat2/Bowtie2 (ALS) or HISAT2 (AD and PD) and quantitated with Cufflinks. PE reads were also aligned using Bowtie2 against genomes from representative species of Toxoplasma gondii and Trichinella sp. T6 (parasitic infectious agents), Babesia microti and Borrelia burgdorferi (tick-vector borne agents), and Treponema denticola and Porphyromonas gingivalis, agents causing chronic gingivitis. Primary aligned reads of each agent in each tissue sample were quantitated with SAMtools. We found small percentages (<0.1%) of transcriptomes aligned with B. microtiB. burgdorferiT. denticola, and P. gingivalis genomes and larger percentages aligned with T. gondii (0.1-0.2%) and Trichinella sp. T6 (1.0-1.1%) genomes. In AD specimens, but in no others, primary aligned transcriptome percentages, although small, approached significance for being greater in AD compared to CTL samples for B. burgdorferi (p = 0.067) and P. gingivalis (p = 0.068). Genes' expressions in postmortem tissues of AD and ALS but not PD revealed significant changes among disease-associated microglial (DAM) genes. Infectious agents' transcripts can be detected in RNA seq reads of both NDD and CTL tissues and vary from agent to agent. Expressions of Stage 1 and Stage 2 DAM genes significantly changed, suggesting the presence of Stages 1 and 2 DAM in our NDD tissue samples.

Tuesday, April 9, 2019

What's known and unknown about Bartonella

Bartonella often comes along with Borrelia (the microbe that is believed to cause Lyme disease), in the same tick. It can also be transmitted by fleas and cats. It can be more destructive than Borellia. Here's a recent update explaining what we know about Bartonella. 

Tuesday, April 2, 2019

New diagnostic tool for early Lyme detection

Unitive Design & Analysis (UDA) are the sole UK contributors to a three year translational project to develop a prototype Point of Care Diagnostic tool to address the growing problem of Lyme disease. 

Saturday, March 30, 2019

Borrelia burgdorferi (sensu lato) in ectoparasites and reptiles in southern Italy.

Parasit Vectors. 2019 Jan 15;12(1):35. doi: 10.1186/s13071-019-3286-1.

Borrelia burgdorferi (sensu lato) in ectoparasites and reptiles in southern Italy.

Mendoza-Roldan JA1,2,3, Colella V1, Lia RP1, Nguyen VL1, Barros-Battesti DM2,4, Iatta R1, Dantas-Torres F1,5, Otranto D6.

Borrelia burgdorferi (sensu lato) is a complex containing pathogenic bacteria of which some species, such as Borrelia lusitaniae, use birds, small mammals and reptiles as reservoirs. In Italy, the bacteria have been detected in reptilian and avian reservoirs in the northern and central regions.

Here, 211 reptiles from three orders [Squamata (Sauria with seven species in five families and Ophidia with 11 species in three families), Crocodylia (one family and two species), and Testudines (two families and two species)] were examined for ectoparasites and molecular detection of B. burgdorferi (s.l.) in three different sites of southern Italy, an area for which no information was previously available on the occurrence of borreliosis in animals and humans. Borrelia lusitaniae was molecularly detected in larvae and nymphs (11.6%) of Ixodes ricinus infesting lizards (i.e. Podarcis muralis, Podarcis siculus and Lacerta bilineata) and in 12.3% blood samples of P. siculus. Finally, B. lusitaniae and Borrelia garinii were detected in 5.1% (32/630) of questing I. ricinus.

These results show the circulation of B. lusitaniae in southern Italy and suggest that P. siculus could play a role as a reservoir, representing a potential medical threat to humans living in or visiting these localities.

Borrelia garinii; Borrelia lusitaniae; Ectoparasites; Ixodes ricinus; Podarcis siculus; Reptiles

PMID: 30646928 PMCID: PMC6332633 DOI: 10.1186/s13071-019-3286-1
Free PMC Article

Thursday, March 28, 2019

A tick-reduction experiment in Nantucket and Martha's Vineyard

Wed Mar 27, 2019 6:43 am (PDT) . Posted by: 

"Rick Laferriere" ri_lymeinfo 

*Mice Against Ticks: an experimental community-guided effort to prevent 
tick-borne disease by altering the shared environment *
Buchthal J, Evans SW, Lunshof J, Telford SR 3rd, Esvelt KM.
/Philosophical Transactions of the Royal Society B: Biological 
Sciences/, 2019 May 13;374(1772):20180105.


Mice Against Ticks is a community-guided ecological engineering project 
that aims to prevent tick-borne disease by using CRISPR-based genome 
editing to heritably immunize the white-footed mice (/Peromyscus 
leucopus/) responsible for infecting many ticks in eastern North 
America. Introducing antibody-encoding resistance alleles into the local 
mouse population is anticipated to disrupt the disease transmission 
cycle for decades.

Technology development is shaped by engagement with community members 
and visitors to the islands of Nantucket and Martha's Vineyard, 
including decisions at project inception about which types of disease 
resistance to pursue. This engagement process has prompted the 
researchers to use only white-footed mouse DNA if possible, meaning the 
current project will not involve gene drive. Instead, engineered mice 
would be released in the spring when the natural population is low, a 
plan unlikely to increase total numbers above the normal maximum in autumn.

Community members are continually asked to share their suggestions and 
concerns, a process that has already identified potential ecological 
consequences unanticipated by the research team that will likely affect 
implementation. As an early example of CRISPR-based ecological 
engineering, Mice Against Ticks aims to start small and simple by 
working with island communities whose mouse populations can be lastingly 
immunized without gene drive.

*Free, full text*:

Wednesday, March 13, 2019

An additional 100,000 tick-bites estimated this year....

And more fun statistics which begs the question: Where did these come from???

About 400,000 new cases of Lyme disease are reported in the United States annually, and about a quarter of those are from New York.  

FYI: Holly Ahern was interviewed for this story.

Sunday, March 10, 2019

Jesse Colin Young and Lyme disease - Q&A: The Solo Years Then & Now

[Jessie Colin Yong] dropped off the charts after the '70s but continued to perform and release new material, some of it quite excellent, until 2006, when his discography suddenly stopped growing.

Now we know why. Young had contracted Lyme disease, which he'd apparently had for years but went undiagnosed until 2009. The debilitating illness kept him out of the game and, adding to his woes, in 1995 his house in his beloved Marin County, California, burned down, leading to Young moving from the area he'd called home since the late '60s. He and his family, including his wife Connie, son Tristan and daughter Jazzie (all of whom are involved in the new album), settled in Hawaii, where Jesse tried a completely new line of work, becoming a coffee farmer.

Today the Youngs live in South Carolina and Jesse is back on the road with the assistance of Tristan, who leads Jesse's new band composed of musicians Tristan met at the Berklee College of Music.

Q: You wrote "Lyme Life," on the new album, about your own experience with the illness.

JCY: There's lot of ugly stuff that happens to you when you get Lyme disease and I do have some dark feelings, but I had to keep [the song] about what needs to be done.

Q: How did the Lyme disease affect your performing and your songwriting?

JCY: When I say in "Lyme Life" that "the shadow left with me," that's kind of what it's like. It makes you crazy. It makes you paranoid. It increased my anxiety level tremendously. Panic attacks. And no doctor seemed to know. I think I may have had this for 20 or 30 years. I got diagnosed in 2009, and the treatment was difficult at times. Luckily by the time my son Tristan was graduating from Berklee College of Music, I was starting to feel like I was getting better, and when songs started to come, I knew something would happen.

Lyme Life:

Friday, March 8, 2019

Former New York Mets pitcher reports Lyme dementia

The New York Times has a policy not to report on Lyme disease as a chronic, degenerative condition. Well, I guess some aspects of the truth just leak through:

Former New York Mets pitcher Tom Seaver reports suffering from dementia as a consequence of Lyme disease.

Thursday, March 7, 2019

Writing New Music Helped Avril Lavigne Live Through Terrifying Illness

I can really relate to this story below. You see, I've been playing piano since I was about 7 years old. When I had my most recent Lyme flareup in 2002, I actually forgot how to play the piano. I could not remember how to coordinate my hands and press the keys and the pedals. Worse yet, all the music I knew so well for decades I couldn't remember. I could not even read music. I remember looking at a Mozart sonata that I had known by memory and I could not decipher the notes on the pages. It just looked like hieroglyphics. I thought I had lost my best friend, my "go-to" comforting activity, for good. Well, I can report that with a lot of care from my LLMDs,  antibiotics, better diet, sleep studies to get my breathing at night working again, and good old Father Time, it all came back to me. I remembered the music I knew, even if my neurological damage made it difficult to coordinate and sit still at times. Maybe brain plasticity moved things around or my brain just needed to de-inflame or babesia had to be brought under control. Who knows? As I healed, I played more and more. I joined a choir in a church and played bass and keyboards there, getting a little better every week. I can say for sure that music is a healer. Listening, playing, singing, dancing — they all helped me tremendously. 

Check out what Avril Lavigne's experience with Lyme and music is/was:

The Canadian singer-songwriter opens up about a terrifying battle with illness and how writing new music saved her life.


Infections of the brain and psychosis
Are psychiatric disorders such as schizophrenia and depression triggered by infections in early life?

Two studies of coconut oil for treating Lyme disease

Here are two studies about coconut oil (and coconut derivatives) for treatment of Lyme disease. 

 2017 Sep;123(3):637-650. doi: 10.1111/jam.13523. Epub 2017 Aug 1.

Reciprocal cooperation of phytochemicals and micronutrients against typical and atypical forms of Borrelia sp.



Borrelia sp., a causative pathogenic factor of Lyme disease (LD), has become a major public health threat. Current treatments based on antibiotics often lead to relapse after their withdrawal. Naturally derived substances that could work synergistically to display higher efficacy compared with the individual components may serve as a resource for the development of novel approaches to combat both active and latent forms of Borrelia sp.


Using checkerboard assay, we investigated the anti-borreliae reciprocal cooperation of phytochemicals and micronutrients against two species of Borrelia selected as prevalent causes of LD in the United States and Europe. 
We tested 28 combinations of phytochemicals such as polyphenols (baicalein, luteolin, rosmarinic acids), fatty acids (monolaurin, cis-2-decenoic acid) and micronutrients (ascorbic acid, cholecalciferol and iodine). The results showed that the combinations of baicalein with luteolin as well as monolaurin with cis-2-decenoic acid expressed synergistic anti-spirochetal effects. 
Moreover, baicalein and luteolin, when combined with rosmarinic acid or iodine, produced additive bacteriostatic and bactericidal effects against typical corkscrew motile spirochaetes and persistent knob/round-shaped forms, respectively. An additive anti-biofilm effect was noticed between baicalein with luteolin and monolaurin with cis-2-decenoic acid. 
Finally, application of the combination of baicalein with luteolin increased cytoplasmic permeability of Borrelia sp. but did not cause DNA damage.


These results show that a specific combination of flavones might play a supporting role in combating Borrelia sp. through either synergistic or additive anti-borreliae effects.


Presented here in vitro results might help advancing our knowledge and improving the approach to target Borrelia sp.
© 2017 The Society for Applied Microbiology.


Borrelia sp.; biofilm; micronutrients; phytochemicals; reciprocal cooperation
[Indexed for MEDLINE] 


 2016 Jul 22;12(9):1093-103. doi: 10.7150/ijbs.16060. eCollection 2016.

Cooperation of Doxycycline with Phytochemicals and Micronutrients Against Active and Persistent Forms of Borrelia sp.

Author information

Dr. Rath Research Institute BV, Santa Clara, California 95050, USA.


Phytochemicals and micronutrients represent a growing theme in antimicrobial defense; however, little is known about their anti-borreliae effects of reciprocal cooperation with antibiotics. A better understanding of this aspect could advance our knowledge and help improve the efficacy of current approaches towards Borrelia sp. In this study, phytochemicals and micronutrients such as baicalein, luteolin, 10-HAD, iodine, rosmarinic acid, and monolaurin, as well as, vitamins D3 and C were tested in a combinations with doxycycline for their in vitro effectiveness against vegetative (spirochetes) and latent (rounded bodies, biofilm) forms of Borrelia burgdorferi and Borrelia garinii. 
Anti-borreliae effects were evaluated according to checkerboard assays and supported by statistical analysis. The results showed that combination of doxycycline with flavones such as baicalein and luteolin exhibited additive effects against all morphological forms of studied Borrelia sp. 
Doxycycline combined with iodine demonstrated additive effects against spirochetes and biofilm, whereas with fatty acids such as monolaurin and 10-HAD it produced FICIs of indifference. 
Additive anti-spirochetal effects were also observed when doxycycline was used with rosmarinic acid and both vitamins D3 and C. Antagonism was not observed in any of the cases. 
This data revealed the intrinsic anti-borreliae activity of doxycycline with tested phytochemicals and micronutrients indicating that their addition may enhance efficacy of this antibiotic in combating Borrelia sp. Especially the addition of flavones balcalein and luteolin to a doxycycline regimen could be explored further in defining more effective treatments against these bacteria.


Borrelia sp.; biofilm; cysts; doxycycline.; phytochemicals; spirochetes
[Indexed for MEDLINE] 
Free PMC Article


Monday, February 25, 2019

Dramatic Recovery In Parkinson’s Patient with Gluten Free Diet

Could gluten's toxicity extend to the nervous system, producing symptoms identical to classical Parkinson's disease? A remarkable case study adds to a growing body of research indicating that wheat's neurotoxicity is greatly underestimated.

A remarkable case report describing the dramatic recovery of a 75-year-old Parkinson's disease patient after following a 3-month long gluten free diet reveals the need to explore whether there is an increased prevalence of silent or symptomatic celiac disease or non-celiac gluten sensitivity both in those afflicted with Parkinson's disease and the related multi-factorial neurodegenerative condition known as Parkinsonism.

Published in the Journal of Neurology,[i] the report notes that celiac disease often manifests with only neurological symptoms, even in advanced age. This may strike the reader as surprising, considering gastrointestinal complaints are the most commonly noticeable symptom; and yet, when the voluminous published literature on gluten related adverse health effects is taken into account, so-called 'out of intestine' expressions of intolerance to gluten-containing grains are far more common than gut-related ones, with no less than 200 distinct adverse health effects implicated. You can read our summary of the biological carnage exacted by this 'king of grains' here: Wheat: 200 Clinically Confirmed Reasons Not To Eat It. You will notice that harm to the brain figures high on the list. From schizophrenia to maniaautism to peripheral neuropathy, the central nervous system is particularly sensitive to its adverse effects.

Read the rest of the story here:

Effect of prolonged antibiotic treatment on cognition in patients with Lyme borreliosis.

Neurology. 2019 Feb 22. pii: 10.1212/WNL.0000000000007186. doi: 10.1212/WNL.0000000000007186. [Epub ahead of print]

Effect of prolonged antibiotic treatment on cognition in patients with Lyme borreliosis.



To investigate whether longer-term antibiotic treatment improves cognitive performance in patients with persistent symptoms attributed to Lyme borreliosis.


Data were collected during the Persistent Lyme Empiric Antibiotic Study Europe (PLEASE) trial, a randomized, placebo-controlled study. Study participants passed performance-validity testing (measure for detecting suboptimal effort) and had persistent symptoms attributed to Lyme borreliosis. All patients received a 2-week open-label regimen of intravenous ceftriaxone before the 12-week blinded oral regimen (doxycycline, clarithromycin/hydroxychloroquine, or placebo). Cognitive performance was assessed at baseline and after 14, 26, and 40 weeks with neuropsychological tests covering the cognitive domains of episodic memory, attention/working memory, verbal fluency, speed of information processing, and executive function.


Baseline characteristics of patients enrolled (n = 239) were comparable in all treatment groups. After 14 weeks, performance on none of the cognitive domains differed significantly between the treatment arms (p = 0.49-0.82). At follow-up, no additional treatment effect (p= 0.35-0.98) or difference between groups (p = 0.37-0.93) was found at any time point. Patients performed significantly better in several cognitive domains at weeks 14, 26, and 40 compared to baseline, but this was not specific to a treatment group.


A 2-week treatment with ceftriaxone followed by a 12-week regimen of doxycycline or clarithromycin/hydroxychloroquine did not lead to better cognitive performance compared to a 2-week regimen of ceftriaxone in patients with Lyme disease-attributed persistent symptoms.




This study provides Class II evidence that longer-term antibiotics in patients with borreliosis-attributed persistent symptoms does not increase cognitive performance compared to shorter-term antibiotics.

Diagnosis and Treatment of Lyme Carditis: JACC Review Topic of the Week

Diagnosis and Treatment of Lyme CarditisJACC Review Topic of the Week


The incidence of Lyme disease, a tick-borne bacterial infection, is dramatically increasing in North America. The diagnosis of Lyme carditis (LC), an early disseminated manifestation of Lyme disease, has important implications for patient management and preventing further extracutaneous complications. High-degree atrioventricular block is the most common presentation of LC, and usually resolves with antibiotic therapy. A systematic approach to the diagnosis of LC in patients with high-degree atrioventricular block will facilitate the identification of this usually transient condition, thus preventing unnecessary implantation of permanent pacemakers in otherwise healthy young individuals.

Sunday, February 24, 2019

Association of small fiber neuropathy and post treatment Lyme disease syndrome

Association of small fiber neuropathy and post treatment Lyme disease syndrome


10 participants, 5/5 women/men, age 51.3 ± 14.7 years, BMI 27.6 ± 7.3 were analyzed. All participants were positive for Lyme infection by CDC criteria. At least one skin biopsy was abnormal in all ten participants. Abnormal ENFD was found in 9 participants, abnormal SGNFD in 5 participants, and both abnormal ENFD and SGNFD were detected in 4 participants. Parasympathetic failure was found in 7 participants and mild or moderate sympathetic adrenergic failure in all participants. Abnormal total CBFv score was found in all ten participants. Low orthostatic CBFv was found in 7 participants, three additional participants had abnormally reduced supine CBFv.


SFN appears to be associated with PTLDS and may be responsible for certain sensory symptoms. In addition, dysautonomia related to SFN and abnormal CBFv also seem to be linked to PTLDS. Reduced orthostatic CBFv can be associated with cerebral hypoperfusion and may lead to cognitive dysfunction. Autonomic failure detected in PTLDS is mild to moderate. SFN evaluation may be useful in PTLDS.

Sue Ferrara, PhD
Hamilton, NJ
Mmi mailing list
Bob Cowart
Phone: 510-540-6667
Lyme disease blog: 
Facebook: bcowart1
Twitter: @bobcowart

Tuesday, February 19, 2019

New video from the Stanford Lyme Working Group

The Stanford Lyme Working Group recently released a 48-minute video about the current research in the area of chronic Lyme disease detection and treatment. There is talk about AIDS research too. I found it pretty interesting.   


Thursday, January 17, 2019

Lone Star Ticks seem to prefer women

Fatal attraction: lone star ticks (Amblyomma americanum) exhibit preference for human female breath over male breath

Ticks use a variety of chemical cues to locate hosts, the main cue being carbon dioxide, which is exhaled by hosts. This study sought to experimentally determine whether ticks exhibit preference among human hosts based on host sex, as the chemical components of human male and female breath have been shown to differ. We focused on the lone star tick, Amblyomma americanum, due to its importance as a disease vector in the United States and its active host-seeking behavior. To test the hypothesis that ticks exhibit preference based upon host sex, we conducted a binary choice behavioral bioassay. Male and female human volunteers (n = 20 pairs) breathed into opposite sides of a secured polycarbonate tube containing 10 adult A. americanum and the proportion of ticks that exhibited a host preference was recorded. We found that under controlled conditions, human females attract a significantly larger proportion of ticks than males. Possible mechanisms to explain these results include that (1) female breath contains components that ticks find attractive, and/or (2) male breath contains a repellent chemical component.